Magnetic system for producing arcuate motions



Dec. 27, 1960 H. SCHACKERT 2,966,106

MAGNETIC SYSTEM FOR paooucma ARCUATE MOTIONS Fig.2

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I N V EN TOR.- l/ezhz Sc/mam United States Patent ce MAGNETIC SYSTEM FOR PRODUCING ARCUATE MOTIONS Heinz Schackert, Krenznach, Rhineland, Germany, as-

signor to Joe. Schneider 8: Co., Kreuznach, Rhineland, Germany, a German company Filed Dec. 27, 1957, Ser. No. 705,587

Claims priority, application Germany Jan. 5, 1957 4 Claims. (Cl. 95-64) My present invention relates to a mechanical system having one or more members movable along an arcuate path, e.g. as used in optical or photographic devices for the purpose of adjusting a diaphragm or some other element centered on a fixed axis.

Heretofore, such orbital movements through a fixed or variable angle of adjustment have usually been eifected manually in one direction and through the intermediary of a suitable restoring spring in the opposite direction. Since manual operation can rarely be performed with uniform pressure and often is not as rapid as actuation by automatic means, it is an object of this invention to provide a system of the character described in which the desired orbital movement is realized by bringing into play a reversible force of predetermined though preferably adjustable magnitude. Another object of this invention is to provide a simple mechanical system of the type referred to in which no springs are needed to propel a controlled element along an arcuate path.

A feature of this invention resides in the provision of two arcuate permanent magnets extending over portions of a common orbit and movable relatively to each other along such orbit, the two magnets having poles of like polarity directed toward each other so that the repulsive force developed between these poles normally maintains the magnets in diametrically opposite positions. If, now, an element of high magnetic permeability, such as an armature of soft iron, is introduced into one of the gaps between the magnets, the system becomes magnetically unbalanced and both magnets will tend to move toward the interposed element. (A like eiiect could be produced by the insertion of a strongly diamagnetic element into the opposite gap.) If both magnets are freely movable, they will both undergo an arcuate displacement; if one is fixed, only the other magnet will so move.

The invention will be described in greater detail with reference to the accompanying drawing in which:

Figs. 1, 2, 3 and 4 are axial views of diiferent magnetic systems embodying the invention; and

Fig. 5 is a radial View of a system generally similar to that of Fig. 4.

In Fig. 1 I have shown two arcuate permanent magnets a and b movable about their common center 0. Each magnet has an extremity c constituting a north pole and an opposite extremity a representing a south pole, the two extremities c and d of like polarities facing each other. Normally, when no disturbing element having a magnetic permeability other than unity is introduced into the system, the two magnets are in balance and the two gaps f and g therebetween are substantially of like width.

If, now, a paramagnetic element such as a soft-iron armature e (Fig. 2) is introduced into gap g, the two magnets a and b will move toward armature e and will come to rest in contact with or at a position close to the latter, depending on whether or not they are stopped by some external abutment not shown. If one magnet,

, 2,966,106 Patented Dec. 27, 196i) e.g. magnet b as shown in Fig. 3, is held stationary, the other magnet (a) alone will execute the arcuate movement toward armature e which in this case is advantageously positioned in close proximity to stationary magnet b. Upon removal of the unbalancing element 2, the magnets will automatically return to their diametrically opposite positions as shown in Fig. 1.

A system as shown in Figs. 1-3 may be used to control an iris diaphragm of a camera objective with preselecteble aperture which is normally held in wide-open position and is momentarily closed down to a previously selected stop position at the instant when a picture is taken, as is well known per -se. Thus, the normal position of the magnets shown in Figs. 1 and 3 may correspond to full diaphragm opening whereas the unbalanced posi tion, e.g. as shown in Fig. 2, represents the selected stop. It will be understood that the extent of the relative movements of the magnets a and b will depend on the depth to which the element e penetrates the magnetic field, e.g. radially as in Fig. 4 or axially as in Fig. 5, and that full insertion of this element into the flux path will cause the magnets to occupy a relative position determined by the width of the element if no external stops are provided. Thus, the selected diaphragm stop may be de termined by the Width of element e and/ or by the extent of its displacement toward the orbit of the magnets. With element e not fully introduced into the field of force, a residual repulsion between extremities a will keep the members a and b from approaching each other to the limit; on the other hand, it is also possible to utilize the wedge-shaped configuration of element e for the purpose of mechanically stopping the magnets in different angular positions depending upon the extent of its radial movement, as will be readily understood.

The angular mobility of either or both magnets a and b may also be utilized, as shown in Fig. 4, for the relative displacement of auxiliary indicator means or the like,

such as a pair of opaque or semi-transparent masking strips m, m" co-operating with a depth-of-ield scale q. Scale q may be linked, as is shown per so, with the focusing control (not shown) of the camera. Reference in this connection is made to commonly assigned application Ser. No. 373,326, filed August 10, 1953, now Patent No. 2,901,956, by Franz Werner, which discloses a depth-of-field indicator of this type.

As illustrated in Fig. 5, the extent of the displacement of armature element e toward the fiux path of magnets a and b may be controlled, e.g. electromechanioally with the aid of a current passing through a coil r, in response to changes in certain ambient conditions, e.g. in the intensity of impinging light as detected by the photovoltaic cell 17 shown in Fig. 5.

It will be apparent that my invention may be modified in various respects without departing from the spirit and scope of the appended claims.

I claim:

1. In a photographic system, in combination, an adjustable diaphragm, a pair of permanent magnets mounted with angular separation for relative movement in a common orbit, said magnets having proximal extremities of like polarities tending to maintain said magnets in diametrically opposite, angularly spaced positions and separated from each other by two gaps, means including at least one of said magnets for controlling said diaphragm, and an armature element of permeability other than unity introducible into one of the gaps between said magnets for relatively displacing said magnets by disturbing the magnetic equilibrium therebetween.

2. In a photographic system, in combination, an adjustable diaphragm, a pair of magnetic members mounted with angular separation for relative movement in a common orbit, said members having proximal extremities of like polarities tending to maintain said members in diametrically opposite, angularly spaced positions and separated from each other by two gaps, means including at least one of said members for controlling said diaphragm, and an armature element of permeability other than unity introducible into one of the gaps between said members for relatively displacing said members by disturbing the magnetic equilibrium therebetween.

3. In a photographic system, in combination, an adjustable diaphragm, a pair of permanent magnets mounted with angular separation for relative movement in a common orbit, said magnets extending over substantially identical arcs of said orbit and having proximal extremities of like polarities tending to maintain said magnets in diametrically opposite, angularly spaced positions and separated from each other by two gaps, means including at least one of said magnets for controlling said diaphragm, and an armature element of permeability other than unity introducible into one of the gaps between said magnets for relatively displacing said magnets by disturb ing the magnetic equilibrium therebetween.

4. In a photographic system, in combination, an adjustable diaphragm, a pair of permanent magnets mouned with angular separation for relative movement in a common orbit, said magnets having proximal extremities of like polarities tending to maintain said magnets in diametrically opposite, angularly spaced positions and separated from each other by two gaps, means including at least one of said magnets for controlling said diaphragm, and an armature element of soft iron introducible into one of the gaps between said magnets for relatively displacing said magnets by disturbing the magnetic equilibrium therebetween.

References Cited in the file of this patent UNITED STATES PATENTS 1,176,399 Needham Mar. 21, 1916 2,091,881 Riszdorfer Aug. 31, 1937 2,163,737 Prinsen June 27, 1939 2,315,977 Mihalyi Apr. 6, 1943 2,556,546 Lee June 12, 1951 2,698,917 Van Urk et al Jan. 4, 1955 2,716,930 Marson Sept. 6, 1955 2,786,971 Tyrell Mar. 26, 1957 2,805,610 Haupt Sept. 10, 1957 2,821,891 Gorey Feb. 4, 1958 2,861,506 Leder et al Nov. 25, 1958 

